1. Field of the Invention
The present invention relates to an RFID system and a communication method thereof, and more particularly, to an RFID system capable of performing high speed data communication between an RFID tag and a reader device, and a communication method thereof.
2. Related Art
Generally, an RFID system indicates a system recognizing tag information stored in an RFID tag by carrier communication between an RFID tag and a reader device. A passive RFID system among the RFID systems indicates a system in which an RFID tag storing object information does not includes a device for communication with a reader device. The RFID tag of the passive RFID system receives a carrier signal form the reader device on a wireless environment to generate its power, thereby performing communication with the reader device based on backscatter.
Since this passive RFID system may provide information of a development object, it may be applied to various fields such as a recognition distance more distant than that of a barcode, simultaneous recognition of a plurality of RFID tags, reading/writing information from/to an RFID tag memory, and the like.
Meanwhile, a region of a technology of the passive RFID system has been gradually expanded from an existing pallet/case level of item recognition to individual item-level-tagging recognition. The RFID system according to the related art has been disclosed in U.S. Pat. No. 5,649,296.
However, in the RFID system according to the related art, in the case in which a technology of the RFID system is applied and expanded to the individual item-level-tagging recognition in accordance with the trend toward the expansion of the function of the RFID system described above, a limitation has been generated in performance and a transmission speed. For example, the following problems are generated.
First, a problem in view of performance in the RFID system according to the related art is that a communication range between the RFID tag and the reader device is short in a low signal to noise ratio (SNR). Second, clear discrimination of auto-correlation of a preamble code that is adopted in the RFID system according to the related art is not present, such that it is difficult to perform long range communication between the RFID tag and the reader device. Third, since the RFID system according to the related art has a transmission speed of 1 Mpbs or less, there is a limitation in satisfying various demands related to high speed recognition of a large number of individual items and reading/writing a large amount of information.